The design, fabrication and performance of a novel silicon lens for Long Wave Infrared (LWIR) imaging are presented. The silicon lenses are planar in nature, and are created using standard wafer scale silicon micro-fabrication processes. The silicon batch processes are used to generate subwavelength structures that introduce spatially varying phase shifts in the incident light. We will show that the silicon lens designs can be extended to produce lenses of varying focal lengths and diameters, thus enabling IR imaging at significantly lower cost and reduced weight and form factor. An optical design program and a Finite-Difference Time-Domain (FDTD) simulation software tool are used to model the lens performance. The effects of polarization anisotropy are computed for the resultant subwavelength structures. Test samples with lenses with focal lengths in the range of 10 to 50 mm were fabricated. The test sample also included a prism structure, which is characterized by measuring the deflection of a CO2 laser beam and compared to theoretical beam deflection. The silicon lenses are used to produce an image on a VGA micro-bolometer array.

Date Published: 17 May 2016
PDF: 8 pages
Proc. SPIE 9822, Advanced Optics for Defense Applications: UV through LWIR, 98220M (17 May 2016); doi: 10.1117/12.2225189

Published in SPIE Proceedings Vol. 9822:
Advanced Optics for Defense Applications: UV through LWIR
Jay N. Vizgaitis; Bjørn F. Andresen; Peter L. Marasco; Jasbinder S. Sanghera; Miguel P. Snyder, Editor(s)